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fw_iptables.go
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/
fw_iptables.go
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package internal
import (
"fmt"
"os"
"os/exec"
"strconv"
"github.com/pkg/errors"
)
const (
IPTablesChainDefault = "OPENSPA-ALLOW"
)
var _ Firewall = &IPTables{}
type IPTables struct {
c CommandExecuter
Settings IPTablesSettings
}
type IPTablesSettings struct {
Chain string
}
var IPTablesSettingsDefault = IPTablesSettings{
Chain: IPTablesChainDefault,
}
func NewIPTables(c CommandExecuter, s IPTablesSettings) *IPTables {
ipt := &IPTables{
c: c,
Settings: s,
}
if ipt.Settings.Chain == "" {
panic("iptables chain is empty")
}
return ipt
}
func (ipt *IPTables) Check() error {
_, err := ipt.c.Execute(iptablesCommand(), nil, "-V")
if err != nil {
return errors.Wrap(err, "iptables")
}
_, err = ipt.c.Execute(ip6tablesCommand(), nil, "-V")
if err != nil {
return errors.Wrap(err, "ip6tables")
}
_, err = ipt.c.Execute(conntrackCommand(), nil, "-V")
if err != nil {
return errors.Wrap(err, "conntrack")
}
return nil
}
func (ipt *IPTables) FirewallSetup() error {
_, err := ipt.c.Execute(iptablesCommand(), nil, "-F", ipt.Settings.Chain)
if err != nil {
_, err := ipt.c.Execute(iptablesCommand(), nil, "--new-chain", ipt.Settings.Chain)
if err != nil {
return errors.Wrap(err, "iptables new chain")
}
}
_, err = ipt.c.Execute(ip6tablesCommand(), nil, "-F", ipt.Settings.Chain)
if err != nil {
_, err := ipt.c.Execute(ip6tablesCommand(), nil, "--new-chain", ipt.Settings.Chain)
if err != nil {
return errors.Wrap(err, "ip6tables new chain")
}
}
return nil
}
func (ipt *IPTables) RuleAdd(r FirewallRule, _ FirewallRuleMetadata) error {
cmd := iptablesCommand()
src6 := isIPv6(r.SrcIP)
dst6 := isIPv6(r.DstIP)
if src6 && dst6 {
cmd = ip6tablesCommand()
} else if src6 != dst6 {
return errors.New("src and dst are not same ip family")
}
var args []string
//nolint:gocritic
if r.Proto == FirewallProtoTCP || r.Proto == FirewallProtoUDP {
args = []string{
"-A", ipt.Settings.Chain,
"-p", r.Proto,
"-s", r.SrcIP.String(),
"-d", r.DstIP.String(),
"--dport", ipt.portString(r),
"-j", "ACCEPT",
}
} else if r.Proto == FirewallProtoICMP || r.Proto == FirewallProtoICMPv6 {
args = []string{
"-A", ipt.Settings.Chain,
"-p", r.Proto,
"-s", r.SrcIP.String(),
"-d", r.DstIP.String(),
"-j", "ACCEPT",
}
} else {
return errors.New("unsupported protocol")
}
_, err := ipt.c.Execute(cmd, nil, args...)
if err != nil {
return errors.Wrap(err, cmd)
}
return nil
}
func (ipt *IPTables) RuleRemove(r FirewallRule, _ FirewallRuleMetadata) error {
cmd := iptablesCommand()
src6 := isIPv6(r.SrcIP)
dst6 := isIPv6(r.DstIP)
if src6 && dst6 {
cmd = ip6tablesCommand()
} else if src6 != dst6 {
return errors.New("src and dst are not same ip family")
}
var iptablesArgs []string
var conntrackArgs []string
//nolint:gocritic
if r.Proto == FirewallProtoTCP || r.Proto == FirewallProtoUDP {
iptablesArgs = []string{
"-D", ipt.Settings.Chain,
"-p", r.Proto,
"-s", r.SrcIP.String(),
"-d", r.DstIP.String(),
"--dport", ipt.portString(r),
"-j", "ACCEPT",
}
conntrackArgs = []string{
"-D",
"-p", r.Proto,
"-s", r.SrcIP.String(),
"-d", r.DstIP.String(),
"--dport", ipt.portString(r),
}
} else if r.Proto == FirewallProtoICMP || r.Proto == FirewallProtoICMPv6 {
iptablesArgs = []string{
"-D", ipt.Settings.Chain,
"-p", r.Proto,
"-s", r.SrcIP.String(),
"-d", r.DstIP.String(),
"-j", "ACCEPT",
}
conntrackArgs = []string{
"-D",
"-p", r.Proto,
"-s", r.SrcIP.String(),
"-d", r.DstIP.String(),
}
} else {
return errors.New("unsupported protocol")
}
_, err := ipt.c.Execute(cmd, nil, iptablesArgs...)
if err != nil {
return errors.Wrap(err, cmd)
}
_, _ = ipt.c.Execute(conntrackCommand(), nil, conntrackArgs...)
return nil
}
func (ipt *IPTables) portString(r FirewallRule) string {
if r.DstPortStart == r.DstPortEnd {
return strconv.Itoa(r.DstPortStart)
}
if r.DstPortEnd == 0 {
return strconv.Itoa(r.DstPortStart)
}
return fmt.Sprintf("%d:%d", r.DstPortStart, r.DstPortEnd)
}
func iptablesCommand() string {
return osEnvLookupOrDefault("IPTABLES_COMMAND", "iptables")
}
func ip6tablesCommand() string {
return osEnvLookupOrDefault("IP6TABLES_COMMAND", "ip6tables")
}
func conntrackCommand() string {
return osEnvLookupOrDefault("CONNTRACK_COMMAND", "conntrack")
}
func osEnvLookupOrDefault(env, defaultVal string) string {
cmd, ok := os.LookupEnv(env)
if !ok {
return defaultVal
}
return cmd
}
func execErrHandle(err error) error {
switch e := err.(type) {
case *exec.Error:
return errors.Wrap(err, "execution")
case *exec.ExitError:
return errors.Wrap(err, "command exit code "+strconv.Itoa(e.ExitCode()))
default:
return errors.Wrap(err, "unknown error")
}
}
func newIPTablesFromServerConfigFirewall(fc ServerConfigFirewall) (*IPTables, error) {
chain := fc.IPTables.Chain
if len(chain) == 0 {
return nil, errors.New("missing chain")
}
ipt := NewIPTables(&CommandExecute{}, IPTablesSettings{
Chain: chain,
})
return ipt, nil
}